Enterotoxigenic Escherichia coli (ETEC) diarrhea is hyperendemic among young Egyptian children, with a balanced distribution of toxin phenotypes from pathogenic isolates. These features make it logical to develop a field site for the evaluation of ETEC epidemiology and ETEC vaccines in Egypt. We have been engaged in a collaborative program of research in lower Egypt designed to characterize ETEC diarrhea in a pediatric cohort and to test the safety and immunogenicity of a promising killed oral ETEC vaccine candidate in preparation for a field trial of vaccine efficacy, which commenced in January 1999.We have followed a cohort of 397 children under 3 years with twice-weekly active surveillance in Abu Homos (Beheira governorate) to determine the age-specific incidence rate of ETEC diarrhea, by toxin and colonization factor (CFA) phenotypes. During 30 months of follow-up of the children, ETEC was isolated in 25% of diarrheal episodes; the incidence rates of ETEC (episodes per child-year) were 1.7, 1.6, and 0.7 in the first, second, and third years of life. Concurrent with establishment of this surveillance, we conducted randomized, placebo-controlled Phase 2 studies of killed oral ETEC vaccine, administered as a two-dose regimen to 76 adults, 107 children aged 6-12 years, 106 children aged 2-5 years, and 95 children aged 6-18 months in Benha, near Cairo. Each of these studies demonstrated the vaccine to be well-tolerated and to induce significant mucosal immune responses to vaccine antigens. In January 1999, a Phase III trial of the vaccine that will assess the safety, immunogenicity, and clinical efficacy of the vaccine, was initiated in Abu Homos. 192 children 6-18 months of age were randomized to receive either vaccine or placebo, and surveillance for potential adverse effects and diarrheal outcomes continues. - Enterotoxigenic Escherichia coli, diarrhea, Egypt, vaccine, clinical trial - Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only